- Synthesis of Disubstituted Cucurbit[6]uril and Its Rotaxane Derivative
-
(Matrix Presented) Synthesis of diphenyl cucurbit[6]uril (CB[6]) has been achieved via co-oligomerization of diphenyl glycoluril and unsubstituted glycoluril. The unsymmetrically substituted CB[6], Ph2CB[B], was further converted to a rotaxane incorporating bis(dinitrophenyl)spermine.
- Isobe, Hiroyuki,Sato, Sota,Nakamura, Eiichi
-
-
Read Online
- Supramolecular assembly of poly(ionic liquid) nanogel driven by host-stabilized charge transfer interaction
-
Poly(ionic liquid) (PIL)-based nanogels, functionalized by naphthyl (Np), are fabricated via a facile one-step ternary crosslinking copolymerization in selective solvent. The size of PIL nanogels can be conveniently regulated through the feed ratio of IL monomer to crosslinker. The presence of Np groups in PIL nanogel is confirmed by using ultraviolet–visible (UV–vis), Fourier transform infrared, and X-ray photoelectron spectroscopy measurements. Through introducing cucurbit[8]uril (CB[8]) and bisviologen compound (DEDV) as the host molecule and electron acceptor, respectively, host-stabilized charge transfer (HSCT) interaction is achieved through utilizing Np containing PIL nanogel as the building block. The studies reveal that PIL nanogels can form schistose aggregates in the scale of micrometer via HSCT interaction. The aggregates will be broken in the presence a competitive guest molecule (amantadine) and can recover by adding another host molecule (CB[7]). HSCT interaction among CB[8], DEDV and PIL nanogel is investigated by dynamic light scattering, UV–vis, and Proton nuclear magnetic resonance. Our studies thus provided an applicable strategy for constructing dynamic polymer nanoparticles through noncovalent interaction.
- Tang, Yuntao,Wang, Ke,Zuo, Yong,Chen, Xi,Xiong, Yubing,Yuan, Yumin
-
p. 2251 - 2259
(2019/11/13)
-
- PROCESS FOR THE PREPARATION OF CUCURBITURIL DERIVATIVES
-
This invention relates to cucurbituril and/or one or more derivatives thereof with low formaldehyde content, to a process of manufacturing said cucurbituril and/or one or more derivatives thereof and to the use of said cucurbituril and/or one or more derivatives thereof, in particular in consumer and industrial products, and in industrial processes.
- -
-
Page/Page column 14; 15
(2018/07/22)
-
- Synthesis and self-assembly processes of monofunctionalized Cucurbit[7]uril
-
We present a building-block approach toward functionalized CB[7] derivatives by the condensation of methylene-bridged glycoluril hexamer 1 and glycoluril bis(cyclic ethers) 2 and 12. The CB[7] derivatives Me 2CB[7] and CyCB[7] are highly soluble in water (264 mM and 181 mM, respectively). As a result of the high intrinsic solubility of Me 2CB[7], it is able to solubilize the insoluble benzimidazole drug albendazole. The reaction of hexamer 1 with glycoluril derivative 12, which bears a primary alkyl chloride group, gives CB[7] derivative 18 in 16% isolated yield. Compound 18 reacts with NaN3 to yield azide-substituted CB[7] 19 in 81% yield, which subsequently undergoes click reaction with propargylammonium chloride (21) to yield CB[7] derivative 20 in 95% yield, which bears a covalently attached triazolyl ammonium group along its equator. The results of NMR spectroscopy (1H, variable-temperature, and DOSY) and electrospray mass spectrometry establish that 20 undergoes self-assembly to form a cyclic tetrameric assembly (204) in aqueous solution. CB[7] derivatives bearing reactive functional groups (e.g., N3, Cl) are now available for incorporation into more complex functional systems.
- Vinciguerra, Brittany,Cao, Liping,Cannon, Joe R.,Zavalij, Peter Y.,Fenselau, Catherine,Isaacs, Lyle
-
supporting information; experimental part
p. 13133 - 13140
(2012/10/08)
-
- Cucurbit[n]uril formation proceeds by step-growth cyclo-oligomerization
-
In contrast to the high yield formation of cucurbit[n]uril (CB[n]) from a 1:2 ratio of glycoluril to formaldehyde, the condensation of glycoluril with less than 2 equiv of formaldehyde delivers a reaction mixture that contains glycoluril oligomers (2-6) and CB[n] compounds that lack one or more methylene bridges known as nor-seco-cucurbit[n]urils (ns-CB[n]). In this paper we report the chromatographic purification of C-shaped glycoluril oligomers (dimer-hexamer), their characterization in solution, and their X-ray crystal structures. Quite interestingly, despite being acyclic glycoluril pentamer 5 and hexamer 6 retain the ability to bind to guests typical of CB[6] but are also able to expand their cavity to accommodate larger guests like cationic adamantane derivatives. We performed product resubmission experiments with glycoluril oligomers 2-6 and found preferences for the formation of specific ring sizes during CB[n] formation. A comprehensive mechanistic scheme is proposed that accounts for the observed formation of 2-6 and ns-CB[n]. Overall, the experiments establish that a step-growth cyclo-oligomerization process operates during CB[n] formation.
- Huang, Wei-Hao,Zavalij, Peter Y.,Isaacs, Lyle
-
supporting information; scheme or table
p. 8446 - 8454
(2009/02/02)
-
- Supramolecular solid-gas complexes: A thermodynamic approach
-
(Table Presented) Phasing up to complex problems: A thermodynamic approach based on solution data has been proposed for the determination of the stability of gas complexes and elucidation of the selectivity of gas binding. Stability constants, reaction enthalpies, and entropies for the complexation of gaseous guests (n-alkylamines) by solid macrocyclic hosts (β-cyclodextrin, cucurbit[6]uril) were calculated by using the Born-Haber type cycle (see picture).
- Grechin, Alexander G.,Buschmann, Hans-Juergen,Schollmeyer, Eckhard
-
p. 6499 - 6501
(2008/09/17)
-
- Mechanism of the conversion of inverted CB[6] to CB[6]
-
(Figure Presented) Inverted cucurbit[n]urils (iCB[n]) form as intermediates during the synthesis of cucurbit[n]urils from glycoluril and formaldehyde in HCl (85°C). Product resubmission experiments establish that the diastereomeric iCB[6] and iCB[7] are kinetic products that are less stable thermodynamically than CB[6] or CB[7] (>2.8 kcal mol-1). When iCB[6] or iCB[7] is heated under aqueous acidic conditions, a preference for ring contraction is noted in the formation of CB[5] and CB[6], respectively. Interestingly, under anhydrous acidic conditions ring size is preserved with iCB[6] delivering CB[6] cleanly. To establish the intramolecular nature of the iCB[6] to CB[6] conversion under anhydrous, but not aqueous, acidic conditions we performed crossover experiments involving mixtures of iCB[6] and its 13C=O labeled isotopomer 13C12-iCB[6]. An unusual diastereomeric CB[6] with a Moebius geometry (13) is proposed as a mechanistic intermediate in the conversion of iCB[6] to CB[6] under anhydrous acidic conditions. The improved mechanistic understanding provided by this study suggests improved routes to CB[n]-type compounds.
- Liu, Simin,Kim, Kimoon,Isaacs, Lyle
-
p. 6840 - 6847
(2008/02/11)
-
- Controlling factors in the synthesis of cucurbituril and its homologues
-
The acid-catalyzed synthesis of cucurbit[n]urils from formaldehyde and glycoluril is poorly understood. In this paper, we examine a wide range of reaction conditions that include the effects of acid type, acid concentration, reactant concentrations, and temperature to both probe the mechanism and optimize the yields of isolated cucurbit[n]urils, where n = 5-10. A mechanism for the formation of these cucurbit[n]urils is presented. Individual cucurbit[n]urils were unambiguously identified in reaction mixtures using ESMS and 13C NMR.
- Day, Anthony,Arnold, Alan P.,Blanch, Rodney J.,Snushall, Barry
-
p. 8094 - 8100
(2007/10/03)
-
- Two mechanisms of slow host-guest complexation between cucurbit[6]uril and cyclohexylmethylamine: pH-Responsive supramolecular kinetics
-
20 times more rapid is the complexation of the organic ammonium ion receptor cucurbit[6]uril (CB6) with cyclohexylmethylamine than with the cyclohexylmethylammonium species (see scheme). Within the narrow pH region around the pKa-value of the amine, the complexation kinetics are accelerated but the binding constant remains essentially unaffected. In this region, the ammonium complex is formed through binding of the amine from followed by fast protonation and not through direct complexation of the ammonium form. Molecular dynamics calculations suggest that the amine form undergoes a direct inclusion into CB6 while the ingression of the ammonium form is retarded by the formation of an association complex, which reacts through a different, higher lying transition state to the inclusion complex.
- Marquez, Cesar,Nau, Werner M.
-
p. 3155 - 3160
(2007/10/03)
-
- Host-guest complexes of cucurbituril with 4-amino-4′-nitroazobenzene and 4,4′-diaminoazobenzene in acidic aqueous solutions
-
The thermodynamics and kinetics of the reaction of cucurbituril (Cuc) with 4-amino-4′-nitroazobenzene (DO3) and 4,4′-diaminoazobenzene (Diam) have been studied in aqueous HCl, and it is shown that DO3 is well suited as an indicator for uncomplexed Cuc (actual concentration of Cuc) and Diam is well suited as an indicator for the total concentration of Cuc (sequestering agent) in aqueous solutions. The formation of 1:1 guest-host complexes is observed. For proton concentrations up to 1 mol dm-3, DO3 reacts according to eqn. (a), with the values for the dissociation constant of DO3H+ log(Ka/dm3 mol-1) = CucH+ + DO3H22+ ? CucH+ + DO3H+ + H+ ? CucH+ + DO3 + 2H+ ? CucDO3H+ + 2H+ (a) -2.42, DO3H22+ log(Kb/dm3 mol-1) = 0.53, for the stability constant of CucDO3H+ log (Kc/mol dm3) = 8.05 and for the rate constant of complex formation log (kf/dm3 mol-1 s-1) = 5.25. Reaction enthalpies and activation energies have also been determined. The complexation of Cuc with Diam has been studied in 0.1-1 mol dm-3 HCl where a very strong complexation has been observed.
- Neugebauer, Roland,Knoche, Wilhelm
-
p. 529 - 534
(2007/10/03)
-
- Catalysis by Cucurbituril. The Significance of Bound-Substrate Destabilization for Induced Triazole Formation
-
A mechanistic investigation is described for the cycloaddition induced between RNH2+CH2CCH and RNH2+CH2CH2N3 (R = H, t-Bu) consequent to encapsulationby the polycyclic molecular receptor cucrbituril (C36H36N24O12).The reaction is shown to be substantially accelerated (ca. 105-fold), and the kinetic characteristics of catalytic saturation behavior, substrate inhibition, and slow product release are documented.For substrates with R = t-Bu a rotaxane product results, and inhibition kinetics with NH3+CH2CH2C(CH3)3 are also examined.A rate enhancementattributed to bound-substrate destabilization is detected.The significance of this effect and its connection with the phenomenon of nonproductive binding in catalytic systems are discussed.
- Mock, William L.,Irra, Ted A.,Wepsiec, James P.,Adhya, Mita
-
p. 5302 - 5308
(2007/10/02)
-